Visual search can be resumed more rapidly following display interruptions than it can be initiated to new displays (Lleras, Rensink & Enns, 2005). Studies of display changes during interruptions suggest these rapid responses are based on perceptual hypotheses regarding task-relevant features of the target (Lleras, Rensink & Enns, in press). Here we use asynchronous feature onsets to reveal the contents of such perceptual hypotheses. We reasoned that briefly delaying the onset of an attribute critical for rapid resumption (RR) would delay such responses.

Participants searched for a target T among L distractors and reported its color (blue, red) as rapidly as possible. Each search item consisted of a black shape (T or L) overlaid by a colored disk. Displays were presented for 100 ms “looks,” interrupted by 1200 ms “waits,” until target color was reported. Three different display types were intermixed across trials: shapes and colors onset and offset simultaneously (standard), black shapes appeared on gray disks for 30 ms before color was added (shape first), and colored disks appeared for 30 ms before shapes were added (color first).

Correct response times (RT) following the first look began after 600 ms but on subsequent looks RT began after 300 ms, a signature of the RR effect. RT distributions for standard and shape-first displays were identical; indicating that delayed onset of color information did not impact RR. In contrast, color-first displays had RT distributions delayed by approximately 100 ms on all epochs after the first look, pointing to the critical role played by shape in the perceptual hypotheses used in target confirmation.

We conclude that asynchronous feature onset in interrupted search tasks can help elucidate the contents of mental representations held during display interruption. We discuss how this paradigm can help reveal representations used in a variety of cognitive tasks.